After my article on training frequency for strength development last week, a lot of people asked whether higher training frequencies were also better for hypertrophy. I responded to all of them that frequency probably doesn’t matter as much for hypertrophy. After all, the two factors that seemed to be the most important for explaining the benefits of frequency for strength development (higher average rep velocity, and increased opportunity to practice motor patterns) don’t seem like they’d matter as much for hypertrophy. I linked a lot of people to Schoenfeld’s 2016 frequency meta-analysis, which found that frequencies of at least twice per week were better than a frequency of just once per week, with insufficient evidence to make conclusions about even higher frequencies. But then I thought more about it, and I realized that the whole reason I wrote my last article was the recent renaissance in the frequency research. So, I got back to the grind to analyze the effects of frequency on hypertrophy.

From the outset, I want to make my pre-existing bias clear. My assumption coming into this article was that, when training volume is equated, higher frequencies were probably beneficial for strength, but probably didn’t matter much for hypertrophy (past a frequency of twice or maybe thrice per week). This bias came from my observations of physical culture (a lot of successful strength training traditions preach higher frequencies, but lower frequencies seem to be the norm for lifters purely focused on hypertrophy), my non-quantitative assessment of the research (several individual studies found significant strength differences in favor of higher frequencies, but very few have found significant hypertrophy differences), and my lack of focus on this issue as a coach (I mostly just train people for strength; hypertrophy is a near-universal side effect, but it’s rarely my primary focus with my athletes).

The subjects needed to be healthy and non-elderly (since age could conceivably affect the relationship between frequency and hypertrophy, as older people recover slower from training).

The study needed to be published in a peer-reviewed journal.

From each study, I pulled all relevant info, including length of the training period, number of subjects, pre- and post-training muscle size measures/estimates, and total sets performed per week. From there, I calculated effect sizes ((post – pre)/(pooled pre-training SD)) and percentage muscle growth ((post – pre)/pre) for each hypertrophy measure in each study. I also calculated percentage hypertrophy per week.

I analyzed these studies several different ways. I started with mixed-effects meta-analyses of effect sizes with frequency as a binary term (i.e. higher frequency vs. lower frequency), including all measures from all studies, just direct measures of hypertrophy, and just indirect measures of hypertrophy. I also calculated the pooled weekly percent hypertrophy and difference between groups for all exercises in all studies as a more easily interpretable meta-analysis, since effect sizes can sometimes seem somewhat abstract. I weighted the percentage-based analyses by the number of subjects in the study, with adjustments for the number of analyses in each study. For example, if a study had 5% of the total subjects in an analysis, and only one measure of hypertrophy, that single measure of hypertrophy would receive a weight of 5%. If, on the other hand, a study had 5% of the total subjects in an analysis, but used five measures of hypertrophy, each of those measures would receive a weight of 1% (so that the total weight of the study would remain 5%).

I made two tables for further analysis: one table of the weekly percentage hypertrophy for each frequency in all studies, and one table of the difference in weekly percentage hypertrophy for each frequency. In this second table, for example, a frequency of three times per week was occasionally the high frequency condition, and occasionally the low frequency condition; this allows for comparisons between a given frequency and all other frequencies (both higher and lower) to see if there’s a frequency “sweet spot” or a range of frequencies that tends to perform best.

As a sub-analysis, I analyzed studies comparing frequencies of once or twice per week to frequencies of 3+ times per week, and studies comparing frequencies of 1-3x per week to 4+ times per week using weekly percent hypertrophy. As further sub-analyses, I analyzed frequency as a binary term using percentage weekly hypertrophy in studies on trained lifters, studies on untrained lifters, estimates of upper body hypertrophy, estimates of lower body hypertrophy, direct measures of hypertrophy, indirect measures of hypertrophy, studies with a low training volume (<10 weekly sets for a given muscle group, or <60 sets per week total), and studies with a high training volume.

Results

Thirteen studies with a total of 305 subjects met the inclusion criteria, allowing for 40 comparisons. The average study was 8.3 weeks long (range: 6-12 weeks) with 10.9 subjects per training group (range: 8-15). Four studies used untrained subjects, while nine used subjects with at least some prior training experience.

The random effects meta-analysis of all hypertrophy measures found that higher training frequencies were associated with significantly more hypertrophy (p<0.0001), though the overall effect was trivial (d=0.113; CI=0.07-0.16). When analyzing only direct or indirect measures of hypertrophy, the story is very similar (d=0.143; CI=0.09-0.19; p<0.0001 for direct, and d=0.097; CI=0.03-0.16; p=0.0098 for indirect).

Direct measures of hypertrophy are blue; indirect measures of hypertrophy are orange. The overall SMD is gray.

On average, subjects in lower frequency groups (N=40 comparisons across 13 studies) grew at a rate of 0.42% per week, while subjects in higher frequency groups grew at a rate of 0.58% per week. The average difference in size gains between groups was 0.16% per week (CI=0.09-0.23%), meaning the higher frequency groups grew about 38% faster, on average (i.e. 0.58% is 38% larger than 0.42%). This would be classified as a small effect (d=0.47; CI=0.25-0.68), and the difference was significant (p<0.0001).

Differences in weekly size gains between higher and lower frequencies. Positive values (blue bars) represent larger gains for higher frequencies, while negative values (red bars) represent larger gains for lower frequencies. The bars that are lighter in color are for indirect measures of hypertrophy, while the bars that are darker are for direct measures of hypertrophy.In this graph and all subsequent graphs like it, blue dots above the black lines represent comparisons where the higher frequency group grew >10% faster than the lower frequency group, red dots below the black lines represent comparisons where the lower frequency group grew >10% faster than the higher frequency group, and yellow dots below the black lines represent comparisons where the high and low frequency groups experienced roughly similar growth. Each dot represents a single measure from a single study. For example, point (0.5%,0.75%) would represent a comparison where the low frequency group grew at a rate of 0.5% per week, while the high frequency group grew at a rate of 0.75% per week.

When using direct measures of hypertrophy (N=19 comparisons across 7 studies), subjects in lower frequency groups grew at a rate of 0.72% per week, while subjects in higher frequency groups grew at a rate of 0.85% per week. The average difference in size gains between groups was 0.12% per week (CI=-0.01-0.26%), meaning the higher frequency groups grew about 17% faster, on average. This would be classified as a small effect (d=0.35; CI=-0.02-0.72), and the difference was not significant (p=0.079).

When using indirect measures of hypertrophy (N=21 comparisons across 9 studies), subjects in lower frequency groups grew at a rate of 0.29% per week, while subjects in higher frequency groups grew at a rate of 0.43% per week. The average difference in size gains between groups was 0.14% per week (CI=0.06-0.22%), meaning the higher frequency groups grew about 49% faster, on average. This would be classified as a medium effect (d=0.72; CI=0.30-1.14), and the difference was significant (p=0.0031).

On average, untrained subjects in lower frequency groups (N=16 comparisons across 4 studies) grew at a rate of 0.39% per week, while subjects in higher frequency groups grew at a rate of 0.58% per week. The average difference in size gains between groups was 0.19% per week (CI=0.09-0.28%), meaning the higher frequency groups grew about 47% faster, on average. This would be classified as a medium effect (d=0.62; CI=0.31-0.94), and the difference was significant (p=0.0014).

On average, trained subjects in lower frequency groups (N=24 comparisons across 9 studies) grew at a rate of 0.44% per week, while subjects in higher frequency groups grew at a rate of 0.58% per week. The average difference in size gains between groups was 0.14% per week (CI=0.04-0.25%), meaning the higher frequency groups grew about 32% faster, on average. This would be classified as a small effect (d=0.38; CI=0.09-0.67), and the difference was significant (p=0.016).

On average, upper body hypertrophy occurred in lower frequency groups (N=17 comparisons across 8 studies) at a rate of 0.42% per week, and occurred in higher frequency groups at a rate of 0.59% per week. The average difference in size gains between groups was 0.17% per week (CI=0.03-0.31%), meaning the higher frequency groups’ upper bodies grew about 40% faster, on average. This would be classified as a medium effect (d=0.50; CI=0.09-0.91), and the difference was significant (p=0.029).

On average, lower body hypertrophy occurred in lower frequency groups (N=14 comparisons across 6 studies) at a rate of 0.65% per week, and occurred in higher frequency groups at a rate of 0.83% per week. The average difference in size gains between groups was 0.18% per week (CI=0.03-0.34%), meaning the higher frequency groups’ lower bodies grew about 28% faster, on average. This would be classified as a small effect (d=0.41; CI=0.06-0.76), and the difference was significant (p=0.038).

Note: this graph makes it look like there’s not much of a difference. However, seven of the points come from a single study, and all the comparisons in that study found either similar gains, or larger gains with lower frequency. The statistical analysis took that into account so that single study wouldn’t get undue weight.This version of the graph only has one data point per study (the average of all measures within that study); it’s a bit more representative of what the statistical model “saw.”

In lower volume studies (N=16 comparisons across 7 studies), subjects in the lower frequency groups grew at a rate of 0.32% per week, on average, while subjects in the higher frequency groups grew at a rate of 0.57% per week. The average difference in size gains between groups was 0.25% per week (CI=0.10-0.40% per week), meaning the higher frequency groups grew about 77% faster, on average. This would be classified as a large effect (d=0.82; CI=0.34-1.30), and the difference was significant (p=0.0046).

This comparison also included the Ochi study with 7 separate comparisons, so I pooled them again here. Note that there are 8 points instead of 7 because one study had both male and female groups, and I represented them separately on this chart.

In higher volume studies (N=24 comparisons across 9 studies), subjects in the lower frequency groups grew at a rate of 0.46% per week, on average, while subjects in the higher frequency groups grew at a rate of 0.58% per week. The average difference in size gains between groups was 0.12% per week (CI=0.03-0.21% per week), meaning the higher frequency groups grew about 27% faster, on average. This would be classified as a small effect (d=0.34; CI=0.08-0.60), and the difference was significant (p=0.017).

Since I pooled the low volume studies when graphing, I pooled the high volume studies as well for the sake of consistency.

When simply looking at average hypertrophy reported with each frequency across all studies, there doesn’t seem to be a significant relationship between frequency and hypertrophy. When running a simple linear regression, the correlation coefficient is basically zero (r=-0.04).

Note: this is the most common general approach for analyzing data like this, but I feel it’s incorrect.

However, as explained in the previous article on the relationship between frequency and strength gains, simply comparing the average hypertrophy seen with different frequencies doesn’t do anything to address the differences in hypertrophy observed between studies. Imagine you have three studies. One compares a frequency of once per week to a frequency of four times per week, the second compares a frequency of three times per week to a frequency of four times per week, and the third compares a frequency of once per week to a frequency of three times per week. In the first study, the low frequency group (1x) grows by 2% and the high frequency group (4x) grows by 4%. In the second study, the low frequency group (3x) grows by 4% and the high frequency group (4x) grows by 6%. In the third study, the low frequency group (1x) grows by 8%, while the high frequency group (3x) grows by 10%. Just averaging the size gains, you see a 5% increase with once per week [(2%+8%)/2], a 7% increase with three times per week[(4%+10%)/2], and a 5% increase [(4%+6%)/2] with four times per week. It looks like 1x per week and 4x per week lead to similar gains, while 3x per week leads to the largest gains; however, those conclusions are driven by differences between studies, not differences between frequencies. With direct comparisons, on the other hand, 1x underperforms both 3x and 4x by 2%, 3x overperforms 1x by 2% and underperforms 4x by 2% (average 0%), and 4x overperforms both 1x and 3x by 2%. This more accurately represents the results in this imaginary trio of studies, because it does a better job accounting for the variability of results between studies.

I feel the direct comparisons (orange dots) better represent the results of these imaginary studies than the simple averages (green dots).

When a frequency of once per week (N=25 comparisons from 10 studies) was directly compared to other frequencies, it slightly underperformed in direct comparisons by 0.079% per week. A frequency of twice per week (N=17 comparisons from 7 studies) slightly underperformed in direct comparisons by 0.080% per week. A frequency of three times per week (N=21 comparisons from 7 studies) essentially performed at par in direct comparisons (minimally outperforming by 0.009% per week). A frequency of four times per week (N=9 comparisons from 2 studies) slightly overperformed by 0.087% per week. A frequency of five times per week (N=7 comparisons from 2 studies) overperformed by 0.310% per week. And finally, a frequency of six times per week overperformed by 0.194% per week, but there was only one measure from one study examining a frequency that high. Since there are fewer studies examining higher frequencies exceeding three times per week, we’ll again pool the results of studies using frequencies of 4+ times per week (N=17 comparisons from 5 studies), finding that they overperformed in direct comparisons by 0.185% per week. Higher frequencies were associated with greater hypertrophy in direct comparisons (r=0.32, p=0.0036).

Given the linear relationship between frequency and hypertrophic overperformance in direct comparisons, I checked the results of studies comparing frequencies of once or twice per week to frequencies of 3+ times per week, and studies comparing frequencies of 1-3 times per week to frequencies of 4+ times per week to verify the results of the regression analysis. Twenty four measures from eight studies were included in the first comparison, and 17 measures from five studies were included in the second comparison. In both comparisons, higher frequency groups experienced significantly faster hypertrophy. The effect size was small (d=0.33) when comparing frequencies 1-2 vs. 3+, and medium (d=0.51) when comparing frequencies of 1-3 vs. 4+.

Since there seems to be a roughly linear relationship between frequency and hypertrophy, we can again analyze slopes to see how much additional hypertrophy one could expect by increasing frequency. Each additional day of frequency increased weekly hypertrophy by 0.11% (CI=0.05-0.16% per week). The average rate of hypertrophy across all frequencies in all studies was 0.50% per week, meaning each additional day of frequency led to 22% more hypertrophy, on average. This slope was significantly different from zero (p=0.0004).

Each blue line represents the slope of the frequency/gains relationship in one study. The red line is the average slope, while the black lines are the top and bottom of the 95% confidence interval. A positive slope means more hypertrophy with higher frequency, while a negative slope means more hypertrophy with lower frequency.

Discussion

First off, I’d like to start by saying that I feel way better about analyzing strength data than hypertrophy data. Strength measures are generally nice and clean, and changes are generally pretty clear. There’s not a ton of measurement error for 1RM tests or torque measurements, and strength gains are typically large enough that you can be confident you’re seeing true changes. Plus, poor adherence to pre-testing guidelines generally won’t screw up strength tests too badly. It’s not going to make a night-and-day difference if someone accidentally drank some caffeine before testing, or if they forgot to show up to the lab fasted (you try to control those things, of course, but sometimes human subjects lie; for strength testing, stuff like that just doesn’t make THAT big of a difference).

With hypertrophy, on the other hand, the changes are typically much smaller (for example, the weekly strength gains in my previous analysis were roughly 4x as large as the weekly hypertrophy in this analysis, even though both analyses used mostly the same set of studies), and sometimes don’t even exceed the measurement error of the device you’re using for testing. Poor adherence to pre-testing guidelines can also make a huge difference, especially for indirect measures of hypertrophy (this is a great article from James Krieger about how to mangle DEXA results). Equipment issues are also worth noting; if you have a good ultrasound unit that shows you really clear fascial boundaries, muscle thickness or CSA measurements are a breeze; if you have an older ultrasound unit, there’s a reasonable amount of guesswork that goes into it.

I say all of this just to note that I have a bit less confidence in these results than I had in my strength results, simply because I’m a bit less trusting of hypertrophy data in general. Collecting good strength data is fairly easy; collecting good hypertrophy data requires more trust in your participants and your equipment, when you’re already trying to find smaller absolute changes or differences.

There also just aren’t any comparisons in this analysis that are as clean as the effects of frequency on upper body pressing strength from the last article. All studies on pressing strength either found larger strength gains with higher frequencies, or similar strength gains regardless of frequency. In this article, all comparisons had at least one study finding >10% more hypertrophy with lower frequency.

Painting in broad strokes, higher frequencies seem to have a larger effect for untrained subjects than trained subjects, for low training volumes than high training volumes, and when you’re assessing hypertrophy using indirect measures (i.e. lean body mass) than direct measures (i.e. muscle thicknesses). Most of the differences were still significant in favor of higher frequencies, but the relative advantage of higher frequencies seems to be smaller if you’re a trained lifter (32% vs. 47% for untrained), if you have high training volumes (27% vs. 77% for low training volumes), and if you’re interested more in growing specific muscles than simply gaining lean mass (17% for direct measures, vs. 49% for indirect measures).

Moving left to right, the lightest color indicates a trivial effect size, the next lightest indicated a small effect size, followed by medium, and then large on the far right.

I think the most obvious explanation would be that higher frequencies allow you to stimulate muscle protein synthesis (MPS) more times throughout the week. Unfortunately, most of the MPS data we have come from studies looking at mixed MPS, whereas myofibrillar MPS is what we really care about. There’s also a dose-response relationship between per-session training volume and per-session MPS (i.e. muscle protein synthesis isn’t just an on/off switch; if you do more volume during a session, MPS will elevate more and be elevated for longer following that session), so it’s not clear that training a muscle more frequently with lower per-session volume actually causes more total MPS throughout an entire week. Now, if that dose-response relationship was really fleshed out, we may be able to use that information for some theory crafting. For example, if we found a plateau in per-session MPS after 5 sets for a given muscle, we may be able to posit, with some degree of confidence, that doing 5 sets, four times per week would be better than 10 sets, twice per week. However, we don’t yet have that level of granularity.

A second potential explanation could simply be higher volumes with higher frequencies. Volume during working sets was equated in all of these studies, but the higher frequency groups would have completed more total warm-up sets over the course of the program. While warm-up sets certainly won’t affect hypertrophy as much as working sets, they still cause some level of training stress.

A third potential explanation may simply be the effort and energy that could be put forth in each set. If you know you have to do a bunch of sets of the same exercise, or if you have to get through a lot of sets within a single training session, it’s natural to hold back a bit at the beginning so you’ll have some energy left at the end of the session, or to start slacking a bit near the end of the session as you start to fatigue (I’m sure that doesn’t apply to you, individually, because I’m sure you’re a total badass. But it’s natural human tendency). Having research assistants present to push the subjects helps rein in these tendencies, of course, but I doubt that completely ameliorated the difference in per-set effort. In one of the studies included in this analysis, per-session internal training load was ~35% lower in the higher frequency group, and total volume load ended up being 16% higher; another study had very similar findings. Another study also found lower ratings of perceived exertion (using an effort-based scale, not a reps-in-reserve based scale) in the higher frequency group. So, we know that the subjects found each session easier, on average, which sometimes translated into higher volume loads, so I think that higher per-set effort probably played an important role.

Two questions came up repeatedly after my strength article that are worth addressing here:

1) Is it OK to train the same muscle on back-to-back days when it’s still sore?

2) Won’t higher frequencies increase injury risk?

Most of the studies looking at the time course of recovery after training find that it can take 2-4+ days for muscles to fully recover after a challenging training session (depending on training status, volume, degree of eccentric stress, etc.). Most people assume that you should wait for a muscle to fully recover before training it again. However, there’s not any good evidence (that I’m aware of) to support that assumption. In fact, there are three studies (one, two, three) comparing consecutive versus nonconsecutive training (i.e. training the same muscles on back-to-back-to-back days, versus resting at least 48 hours between training sessions for the same muscle group), and none of the three have found any negative effects for consecutive training. Now, all three of those studies used untrained or recreationally trained lifters, but they’re the only direct evidence we have. Also, keep in mind that with higher frequencies, per-session volume per muscle group should be lower, which makes training the same muscle on back-to-back days much more doable.

As for injury risk, I think there’s a scientifically correct answer, and a practically correct answer.

A recent study in powerlifters found pretty weak associations between training frequency and injury risk (in some analyses, there was a positive association; and in some analyses, there was a negative association). Furthermore, most acute injuries tend to occur when you’re fatigued, and focus or motor control start slipping, so I’d assume that higher frequencies may decrease acute injury risk by decreasing per-session volume. I think the effect of frequency on chronic injury risk would largely be determined by technical proficiency. With good technique, I doubt higher frequencies would increase chronic injury risk. With poor technique, though, it wouldn’t surprise me if higher frequencies increased chronic injury risk by frequently exposing your tendons and/or ligaments to excessive stress. That’s the scientific answer.

The practical answer is that is probably depends on how you approach training psychologically. If you like to go all-out on every set and keep per-session volume high for each muscle group you train so that you feel like you’ve really thrashed yourself by the end of a workout, high frequencies are probably a very bad idea for you. If you take a more relaxed approach to training (and lift with good technique), you’ll probably be fine with higher frequencies.

There’s one final issue I want to address before wrapping up: If you’re a Weightology subscriber, you probably know that James Krieger has a guide covering this same topic (and if you’re not a Weightology subscriber, you should rectify that issue right after you subscribe to MASS). If you’ve read it, you’ll probably also notice that our results differ. There are a few reasons for that:

1) James includes a few studies that I don’t. There’s a study by Arazi and Abbas I didn’t include because it doesn’t include any information about training volume. His analysis also includes a few unpublished studies that are currently in review.

2) When analyzing the dose-response relationship between frequency and hypertrophy, it seems that James is pooling the effect sizes and percent increases with each frequency, rather than analyzing how each frequency performs in direct comparisons against other frequencies. That is certainly the standard approach, but as I explained in this article, I think it’s more apt to pick up differences between studies, rather than differences between frequencies within those studies.

Edit: I spoke with James, and he said he model does also model between-study variance. I’d need to dig into the nuts and bolts of his model more to fully understand the issue, then, because our results differ drastically.

3) For these analyses, I tend to take a slightly more liberal (but certainly still valid) statistical approach than James. My reasoning for this is that my audience is primarily composed of lifters and coaches, and I think lifters and coaches should approach type I and type II error differently than scientists.

[ A brief philosophy of science interlude ]

In science, a type I error – a false positive – is the type of error you aim to avoid at all costs. On the other hand, a type II error – a false negative – is much more acceptable. If A is not different from B, but you say it is, that’s really bad. If A is different from B, but you say it isn’t, that’s not nearly as big of a deal. There are a few reasons that science is oriented this way, but the main purpose is to keep people from spending a ton of time and research dollars attempting to investigate and flesh out an idea that wasn’t true in the first place. Science is a self-correcting process, but you really want to make sure that most of the time and resources within the sciences are spent making actual progress, not self-correcting avoidable mistakes. The stakes are often quite high as well. If you’re developing a new drug, you want to be really confident it’s better than the currently prescribed drug that it’s replacing, because being wrong could cost lives.

For an athlete or coach, the calculus is different. The stakes are generally lower (it’s not a life-or-death situation; you’ll probably be able to make gains with any training frequency), and the standard of evidence you should require before making a decision should be lower as well. When troubleshooting a lifter’s training program, you rarely have the luxury of waiting to try something new until you’re 95%+ confident you’re making the absolute optimal choice for that athlete. If you’re 70% sure something will help, and the costs or risks associated with that decision are minimal, it typically makes sense to pull the trigger. Type II errors (the opportunity cost of forgoing something that could have helped) are just as costly as type I errors (trying something that doesn’t help).

With all of that being said, the analyses I run are still kosher procedures that certainly prioritize limiting Type I errors. I’m still calculating confidence intervals and aiming to reject a null hypothesis (a maximally liberal approach would involve just comparing mean point estimates). They’re just not quite as conservative as James’ analyses, because I also don’t want to unnecessarily inflate type II error, given the audience of this site and the purpose of my articles (making recommendations that have the highest probability of being helpful for athletes and coaches).

[/end interlude]

As one final point before we wrap up: I think the volume-matched literature (reviewed in this article) may underestimate the effects of frequency on hypertrophy. We know that volume seems to be the largest driver of hypertrophy, and generally increases in frequency allow for increases in volume. Doing 20 sets of squats in a single session will mangle most people, but doing 5 sets of squats, four times per week is generally challenging but doable. I do think that higher frequencies may increase the risk inherent in increasing volume, though. If you only train legs once per week and you go overboard in one session, at least you have a week to recover before training legs again; most people can recover from damn near anything in a week. If you train legs four times per week and your volume is too high, however, it’s easier to keep digging yourself deeper and deeper into a hole, increasing your risk of overreaching or overtraining. So, increasing frequency can be beneficial, but you need to be smart about it. Effectively monitoring recovery probably becomes more important with higher training frequencies.

Practical Recommendations for Training Frequency

So, let’s end with some practical recommendations:

1) If you’re currently making progress on a low frequency training program, don’t change anything. When you plateau, however, consider increasing your training frequency.

2) Many lifters, anecdotally, find that they can tolerate higher frequencies for some exercises or muscle groups but not others. Higher training frequencies are worth a shot, but keep in mind that your personal responses may not mirror the average response.

3) If you increase your training frequency, start by distributing your current training volume over more days per week. Don’t increase volume until you see how you respond and how well you can recover between sessions.

4) If training purely for hypertrophy with a high frequency, consider alternating between more and less taxing exercises for each muscle group. For example, if you do squats on Monday to train quads, do something lighter like step-ups or split squats on Tuesday or Wednesday.

5) I’d primarily recommend higher frequencies when training to bring up weak points, or when weekly volume for a given muscle group is low. They’re useful in other contexts, but those are the situations where I think they’d give you the largest return on investment.

If you’ve made it this far, you should consider signing up for Monthly Applications in Strength Sport. It’s a research review that Eric Helms, Mike Zourdos, and I publish every month, breaking down the recent research that’s most relevant and useful for strength and physique athletes and coaches. You can snag a free issue here if you’d like to check it out.

Related

About Greg Nuckols

Greg Nuckols has over a decade of experience under the bar, a BS in Exercise and Sports Science, and a Master's in Exercise Physiology. He’s held 3 all-time world records in powerlifting in the 220 and 242 classes.

He’s trained hundreds of athletes and regular folks, both online and in-person. He’s written for many of the major magazines and websites in the fitness industry, including Men’s Health, Men’s Fitness, Muscle & Fitness, Bodybuilding.com, T-Nation, and Schwarzenegger.com. Furthermore, he’s had the opportunity to work with and learn from numerous record holders, champion athletes, and collegiate and professional strength and conditioning coaches through his previous job as Chief Content Director for Juggernaut Training Systems and current full-time work here on Stronger By Science.

His passions are making complex information easily understandable for athletes, coaches, and fitness enthusiasts, helping people reach their strength and fitness goals, and drinking great beer.

Reader Interactions

Comments

Let’s say someone is in the habit of going to the gym 3x per week (M/W/F) and they’re interested in increasing volume/frequency to bring up their chest, say. Would it make sense to recommend that they just do a few sets of push-ups on their rest days? That would allow them to alternate between more challenging workouts and easier ones, and it would allow them to increase frequency with just a few extra minutes devoted to training each day.

(My goal here is to figure out the easiest possible way to get ideal results, trying to optimize both the likelihood of compliance as well as progress.)

The general consensus at this point is that the primary driver of hypertrophy is volume. You personally once proposed the notion of using “hard sets” to track volume, and Mike Israetel prefers a similar approach. Can we assume, based upon these prior assertions, that the absolute load an individual handles does not have a direct impact on hypertrophy? I.e. if I once squatted 100 kg for 3 hard sets of 8 and now I currently squat 140 kg for 3 hard sets of 8, that is a strong indication I have gained muscle; but is it likely that squatting 140 kg for 3×8 will have a greater hypertrophic outcome for me, personally, in comparison to the hypertrophy that I was once able to achieve squatting 100kg? To put it more simply, the 140kg 3×8 gives me what 100kg used to give me, but not more, correct?

I ask all of this to inquire, then: if a program leads to greater strength outcomes over time (ie a higher frequency program, for example) does that equate to greater hypertrophic outcomes over time? If the answer is no, is that because the increases in absolute load do not necessarily yield corresponding increases in growth? This feel confusing for me because I believe the above paragraph to be true…but I also believe that if my 8-12 RMs are increasing, I am growing, and if they were to increase more quickly I would likely conclude I was growing faster.

>To put it more simply, the 140kg 3×8 gives me what 100kg used to give me, but not more, correct?

Correct, to a point. I mean, it’ll probably give you less than 100kg used to, simply because hypertrophy slows down over time, but it’ll give you the same amount of growth, relative to the total rate of growth you could reasonable expect.

>I ask all of this to inquire, then: if a program leads to greater strength outcomes over time (ie a higher frequency program, for example) does that equate to greater hypertrophic outcomes over time? If the answer is no, is that because the increases in absolute load do not necessarily yield corresponding increases in growth? This feel confusing for me because I believe the above paragraph to be true…but I also believe that if my 8-12 RMs are increasing, I am growing, and if they were to increase more quickly I would likely conclude I was growing faster.

I think you can view this two different ways. If you’re manipulating a particular variable with the primary aim of driving strength gains (i.e. if you switch from doing higher rep sets to a bunch of heavy singles or doubles), I don’t think the corresponding increases in strength also indicate faster hypertrophy. However, if you still have a generally “hypertrophy-focused” program and strength starts increasing faster, I do think that tends to be indicative of faster hypertrophy. With frequency, specifically, I’m not totally sure, though. Maybe the increased hypertrophy is the main driver of the larger strength increases (so conversely, faster strength increases would be indicative of more hypertrophy), or maybe it’s moreso the increased frequency of practice improving skill acquisition (which probably wouldn’t be related to hypertrohy). I should see whether the studies that report the largest hypertrophy differences are also the studies reporting the largest strength differences within this analysis. I’m pretty busy for the time being, but remind me in a week. I should have time then.

Thanks for the detailed response! And that makes sense, since strength gains are only correlated with hypertrophy, there are undoubtably strategies that disproportionately impact strength vice hypertrophy—and frequency is potentially one of them. Would be curious about the question you posed if you have/had time to look into it

Old school methods best. Use extremely low reps 2-3 in starting exercise and as moving into heavier weights as u move up towards max,cut to 1 rep add weight and do 1 rep til hit max highest lift. Now only if u want to bodybuilder.Very and increase size of muscle worked, rep out only after dropping 25-30 lbs. Do another set again,and drop more poundage and rep out again. This is done to fatigue that muscle and pump it with blood. So, no reps for strength,and many reps with heavy and medium for size and shape and definition. Pyramid training.My lazy brother used to do one rep bench,add 2 lbs do 1 rep and add weight and continue to his max. He weighed 145,skinny arms,no muscle,but strengthened his tendons and ligaments and benched 300lbs in several months. I gained 120lbs in 3 mos,using the pyramid plan,3 times week.in bench press. Always had strenghth,size and shape.All natural,no drugs. Did 400lbs.bench,320 incline.400lb.deadlift,175lb barbell curl at 215 lb bodyweight. 52in.chest 1 in arms.This work all done in 60 my twenties.Still workout,at age 78, 4-5 days.wk.

I’m 57 years old and I’m returning to weight lifting after several periods in the past from middle high school to around 40 years old training with weights. I had been considering much higher frequency when I recalled a friend I had in High school back in the late 70s. He trained the same muscles every day and was by far the most muscular kid in our high school! Now, with this article, I’m seeing some verification of his method which a lot of others back then thought was misguided but couldn’t argue with his results. I’m talking about large, full, well defined muscles that he had. Very strong as well but I don’t recall the numbers he could put up except that they were higher than most others. His workouts were several hours long as well.

I remember that was popular back in the day. The guys I saw doing it were always big and I did it a little myself. It made sense to cover a full range of reps and be able to handle some very heavy weight as well as pump up the muscle. You get both in, seems like a good way to go.

Hi Greg,
I’ve been thinking a lot about frequency in the recent weeks, for strength as well as mass, and how to increase it across my current plan without sacrificing volume or adding additional training days. Do you think week by week cycling could work? For example, week A with 20 sets of squats distributed across 4 days, followed by week B with 10 sets across 2 days and then back to week A? Both weeks themselves would be on a volume/intensity progression.

I was curious whether I might see an increased response by using frequency spikes (4 to 2 times a week) alternated with kind of rest periods (2 to 0 times a week) on a weekly schedule instead of just doing the average every week.

I probably wouldn’t alternate that frequently, but yes, I think that approach can work. What I’ll often do is train one lift with high frequency and higher volumes for 4-6 weeks, and decrease frequency and volume on the other lifts to compensate. After that, I’ll generally either move all lifts back to more “normal” volumes and frequencies for a few weeks, and then move to a new block focusing on another lift.

Hi Greg,
just a hypothetical question,
when volume is equated in higher frequency ( suppose 5x/wk) training , will there be much difference between a single training session against a 2x or 3x per day in terms of hypertrophy? eg: suppose for an olympiclifting squats 15 sets/week on a 3 sets/day with 3 working sets against it split off into one working set morning, noon, evening. (exclude the effect of the warmup sets, ) .
or will it turn into a bulgarian type training method?
or will not get enough training stimulus to activate MPS??

I appreciate that, as a good scientist, you clearly lay out the limitations of the analyses you (and others) performed and interpret the results with an appropriate degree of caution.

I also like your speculation that MPS may be more pronounced after a higher volume session than after a lower volume session, which may thus make the differences in hypertrophy between high and low frequency training less dramatic than one might expect given the typical MPS argument for high frequency training. I think this issue should be next on the agenda for research.

Assuming that older lifters would require more days to recover from their lifting sessions, I wonder if you might predict that they would benefit more from a lower frequency approach.

For older populations, I believe most of the research supports ~2 hard sessions per week. Cody Haun (one of our coaches) was involved in a study on elderly adults which basically tested three hard sessions per week against two hard sessions and one substantially easier session, and they found more hypertrophy (and larger strength gains, if memory serves) with the second set-up.

I’m 57 years old and I’m returning to weight lifting after several periods in the past from middle high school to around 40 years old training with weights. I had been considering much higher frequency when I recalled a friend I had in High school back in the late 70s. He trained the same muscles every day and was by far the most muscular kid in our high school! Now, with this article, I’m seeing some verification of his method which a lot of others back then thought was misguided but couldn’t argue with his results. I’m talking about large, full, well defined muscles that he had. Very strong as well but I don’t recall the numbers he could put up except that they were higher than most others. His workouts were several hours long as well.

Hi Greg, You mention several variables that were probably measured with large error, or not measured at all. Why is blood chemistry not measured as in other papers? I believe this has much more precision and shows the real damage and recovery. Based on https://jissn.biomedcentral.com/articles/10.1186/1550-2783-9-20 the graphs and charts indicate any measurement of size will actually be measuring INFLAMMATION! unless measured after at least 72 hours after exercise (in the best cases, 96 hours to be certain). I would also like to see the gage R&R of these measurements types. If you look closer to the jump heights (Table 1) it is easy to see that recovery is several days at minimum. therefore based on the chemistry, recovery of function and strength, wouldn’t it be premature to advise more than 2 times per week?
PS My wife is an ultrasound tech, variation is extremely high for these measurements!

Correct me if I’m wrong, but it seems that you’re assuming that people shouldn’t train a particular muscle/movement again unless they’re fully recovered from the previous session. Is that correct?

As for muscle swelling post-training, researchers are aware of that, and most studies wait at least 72 hours after the last training session before taking post-training ultrasound measurements or doing post-training body comp assessments.

Hi Greg Nucklos. I wrote this in “non-responders” post. Sorry for my poor english, I learn this.

9 years in the gym = zero strength and muscle growth.
Surplus in diet? Making fat on belly.
All life on low carb.
Every carbohydrate and surplus (from fat, from carbs) makes me fat.
Strength like a child.
Systematic training.
Low testosterone.
Thyroid? Okay.
After training on the second day, I feel like I have flu.
9 years of training, but DOMS is still there.
Even a bodybuilder (from the stage) has no help for me (They made me diet and workouts.).
Bodybuilder coach told me that: You are eating while eating air. I make fat so easily.

Hi Greg, thanks for answering and providing a forum for discussion.
Correct, don’t work out the muscle again until recovery. There are lots of reasons, especially when you read so many suggesting adding weight every workout, when obviously the unrecovered muscle is not capable of as much work as the previous undamaged state.
The chemistry of cytokines possibly reduces immune responses. Wouldn’t it be a problem for athletes to damage their muscles within a day or two prior to competing? wouldn’t measuring the Cytokine reaction be a better gauge than “feelings” or other measurements? This could change a lot of approaches and help optimize for atheletes and others. I bet there are differences in age ranges too.
Then this becomes a real technical issue, easily measured via simple blood chemistry test.
There will be a few things to answer depending on the application, does the damaged muscle grow more when continuously damaged, or is it damaged further. when is a rest period required. Naturally everything changes with the use of steroids, even the amount of satellite cells, etc.

Thus far, none of the studies that have actually investigated the effects of training the same muscles on back-to-back-to-back days vs. resting at least 48 hours between workouts have found any ill effects from training a muscle again before it’s fully recovered, so I tend to think it doesn’t matter all that much.

Thanks Greg http://www.lookgreatnaked.com/blog/
Looks like Brad has the answer here in his blog. “there is evidence that just one additional bout of the same exercise protocol reduces the swelling response to only one-third of the initial bout.” So damage is reduced as more damage is sustained, makes sense. compares their measurements and finds that there may some measurement issues by not waiting long enough to make sure swelling is completed.
Other studies are discussed, there was some dose response, but comparisons diverged on the higher levels. Shoenfeld’s results were 1/4 of another study. Heselgrave study is interesting, the intermediate level was best? But two confounding variables present. “In summing up the literature to date, the one thing that appears clear is that volume plays a fairly prominent role in maximizing growth, but nevertheless significant hypertrophy can be obtained at fairly low volumes.” The second blog entry also has some great points for reference.

Are these muscles trained to failure? Also, do you do high-volume sets every week, with each set going to failure, and then wait for that trained muscle group to recover? Would that lead to more muscle hypertrophy than fewer sets taken to failure?
In this case, is there an “upper limit” to how many sets can be done each week, before the point of diminishing returns?? If you do more that x number of sets per week, you have overtrained and diminished your muscle growth potential?

Thanks for sharing this helpful information. You are inspiring me for muscle growth. I’m sure most people can take notes from this article. One thing most people lack the experience of muscle growth. Well, this post gives me some good ideas for muscle growth.

Late to the party, but could the difference in growth results between upper body and lower body workout frequency simply be a matter of casual, everyday use? For example, although an activity like walking is obviously way less intense than lifting weights, it still sort of counts as muscle use, and if warm up sets can count as “weekly volume” maybe walking does as well. Depends on your job and life, but I’d say most people don’t have an upper body “equivalent” to walking that must be used every day that could count towards muscle use frequency, if you get what I mean.

In other words, do you think that simple movements like walking, standing up from your chair, etc is counting as muscle-use frequency, which is what explains why lower frequency lower-body routines are comparatively more effective than upper-body routines?

I am so grateful I found your post, You’ve really covered up almost all the possible tips that a beginner should follow while want to muscle growth. Actually, I got a lot of information from your blog which can help me make my muscle better. Thanks.

I love reading your posts online but would love to be able to print them out to read. Have you thought about attaching a downloadable PDF version of the article along to the page to set up a printable option?

I was wondering, Greg, what you thought of the idea that beginners should do the minimum volume required in order to keep making gains? My worry is that ‘desensitising’ muscle to higher volume training early in the trainee’s career, at a time when lower volumes may suffice regardless, may give the trainee less room to increase volume as their career progresses.

Let us say that beginner A was doing 14 challenging sets of bench a week (6 sets twice a week), while beginner B was doing 6 challenging sets (3 sets twice a week). When beginner B stalls, he can move the volume up to 7, 8, 9 sets etc and has a lot of wiggle room to increase volume and keep grinding out gains for quite a while, while beginner A will increase to 15, 16, 17 sets and so on and eventually run out of room to increase volume, hampering his progress.

I also have a friend who bumped his bench from 75kg to 100kg over the course of a few months by benching 7-9 high intensity sets 4 times a week. Is there a risk that he will, from now on, require similarly high volume, high intensity and high frequency to get his bench to budge any higher? Would he have been better off training more conservatively and giving himself more room to upscale his training in the future?

I think it’s a question of time scale. Like, is there a possibility that you may need to take a bit of time to train with lower volumes to re-sensitize yourself to higher volumes? Sure. Will that negatively impact long-term development? As long as you don’t sustain a bunch of injuries in the process, I highly doubt it. If that were true, once you plateaued with the highest volume you could tolerate at a given point in time, you’d just be stuck forever. That’s not what happened in the real world. Heck, my volume when I totaled 1885 was way lower than when my total was 1525.

Awesome, Greg, really appreciate the response. It’s reassuring to know that you’re not stuck when you max out tolerable volume and that training with higher volume early in one’s career is unlikely to have any significant implications later on.

The reason I asked is actually because of something mentioned by Lyle McDonald in his articles about his bulking programs. He said it was important to minimise volume to the lowest effective dose in order to give room for escalation/progression as needed later on.

However, if you can later scale back volume and ‘resensitise’ the muscle to making gains with a lower number of difficult sets, I don’t see why this matters at all.

Yeah. I’ve talked to a lot of extremely high-level lifters (world-class folks, in an array of strength sports). With very few exceptions, all of us fell in love with lifting a little too hard, and went through a period of training WAY too much. That wasn’t the end of the road, progress-wise, for anyone. I’m aware of very few biological systems that become desensitized to something, that can’t also become re-sensitized.

An overlooked issue is low frequency fatigue or LFF (fibers that fire in the 10hz to 40hz range). The low frequency fibers do not recover as quickly as the high frequency fibers,which can take days to occur as opposed to hours of the higher frequency fibers which can drastically affect muscle output performance.

[…] We have pretty solid data showing that muscle group training frequencies of 2-3x/week provide superior hypertrophy when compared to volume-matched frequencies of 1x/week [7]. Additionally, there may be a dose response relationship between frequency and hypertrophy, even when volume matched, going above 2-3x/week (check out Greg’s in house meta). […]

[…] practice is set- but not work- or repetition-equated studies. This is what Greg Nuckols did in his recent unofficial meta-analysis on training frequency, which found significantly greater muscle growth with higher training […]

[…] is set- however now not work- or repetition-equated research. This is what Greg Nuckols did in his contemporary unofficial meta-analysis on coaching frequency, which discovered greatly better muscle expansion with upper coaching […]

[…] is set- however now not work- or repetition-equated research. This is what Greg Nuckols did in his fresh unofficial meta-analysis on coaching frequency, which discovered greatly larger muscle expansion with upper coaching […]

[…] set- however no longer work- or repetition-equated research. This is what Greg Nuckols did in his fresh unofficial meta-analysis on coaching frequency, which discovered greatly larger muscle enlargement with upper coaching […]

[…] set- however no longer work- or repetition-equated research. This is what Greg Nuckols did in his fresh unofficial meta-analysis on coaching frequency, which discovered greatly higher muscle enlargement with upper coaching […]

[…] is set- however now not work- or repetition-equated research. This is what Greg Nuckols did in his contemporary unofficial meta-analysis on coaching frequency, which discovered drastically better muscle enlargement with upper coaching […]